Goveia VR, Mendoza IYQ, Guimarães GL, Ercole FF, Couto BRGM, Leite EMM, et al.
1 Universidade Federal de Minas Gerais, Escola de Enfermagem, Belo Horizonte, MG, Brazil.
2 Centro Universitário de Belo Horizonte, Instituto de Engenharia e Tecnologia, Belo Horizonte, MG, Brazil.
3 Universidade Federal de Minas Gerais, Hospital Risoleta Tolentino Neves, Belo Horizonte, MG, Brazil. 4 Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Belo Horizonte, MG, Brazil.
ABSTRACT
Objective: To investigate endotoxins in sterilized surgical instruments used in hip arthroplasties. Method: A descriptive exploratory study conducted in a public teaching hospital. Six types of surgical instruments were selected, namely: acetabulum rasp, femoral rasp, femoral head remover, chisel box, lexible bone reamer and femoral head test. he selection was based on the analysis of the diiculty in removing bone and blood residues during cleaning. he sample was made up of 60 surgical instruments, which were tested for endotoxins in three diferent stages. he EndosafeTM Gel-Clot LAL (Limulus
Amebocyte Lysate method) was used. Result: here was consistent gel formation with positive analysis in eight instruments, corresponding to 13.3%, being four femoral rasps and four bone reamers. Conclusion: Endotoxins in quantity ≥0.125 UE/mL were detected in 13.3% of the instruments tested.
DESCRIPTORS
Endotoxins; Surgical Instruments; Arthroplasty, Replacement, Hip; Orthopedic Nursing; Operating Room Nursing.
Endotoxins in surgical instruments of hip arthroplasty
Endotoxinas em instrumentais cirúrgicos de artroplastia do quadril Endotoxinas en instrumentales quirúrgicos de artroplastia de la cadera
Vania Regina Goveia1, Isabel Yovana Quispe Mendoza1, Gilberto Lima Guimarães1, Flavia Falci Ercole1, Bráulio Roberto
Gonçalves Marinho Couto2, Edna Marilea Meireles Leite3, Maria Aparecida Resende Stoianoff 4, José Antonio Guimarães
Ferreira4
How to cite this article:
Goveia VR, Mendoza IYQ, Guimarães GL, Ercole FF, Couto BRGM, Leite EMM, et al. Endotoxins in surgical instruments of hip arthroplasty. Rev Esc Enferm USP. 2016;50(3):405-410. DOI: http://dx.doi.org/10.1590/S0080-623420160000400005
Received: 12/09/2015 Approved: 04/20/2016
ORIGINAL ARTICLE DOI: http://dx.doi.org/10.1590/S0080-623420160000400005
Corresponding author: Vania Regina Goveia
Escola de Enfermagem, Universidade Federal de Minas Gerais
Endotoxins in surgical instruments of hip arthroplasty
INTRODUCTION
Joint replacement surgeries using orthopedic implants bring beneits to patients, such as pain relief and recovery of movements. However, they require long-term follow-up to determine their efectiveness and safety, since they might involve complications(1-2).
here are two laws associated with orthopedic implants. he irst is of mechanical nature, resulting from the exces-sive use of the prosthesis, its displacement or misalignment, physical stress and bone fracture. he second is of biologi-cal nature, caused by inlammation due to the presence of particles where the prosthesis is located. Although infection is one of the causes for the loosening of a prosthesis in about 1.5% of the patients, a non-infectious complication or aseptic loosening is the main cause of surgical revision(3-5).
In the United States, 500,000 arthroplasties are per-formed every year; of these, 40,000 undergo through revi-sions due to aseptic loosening, often associated with the presence of endotoxins. Presence of osteolysis around the prosthesis is observed in aseptic loosening, due to the pres-ence of particles generated from the implant. If endotoxins are present, they adhere to these particles, being probably one more factor to inducing the loosening. Endotoxins are found in the outermost membrane of Gram-negative bacte-ria and belong to the phospholipids class called lipopolysac-charides (LPS). heir release occurs due to the cell death, but there is evidence that it happens in a lower proportion, during the process of cell growth and division(3-7).
hese indings suggest the need to know the endotox-ins’ role in these situations of inlammatory response, where there are not clinical and microbiological signs of infec-tion. Initially, it might seem contradictory to address aseptic loosening without excluding the presence of a subclinical level of bacteria that may colonize orthopedic implants, form bioilm and be the source of endotoxins(5).
he limit of endotoxins in health devices was regu-lated by the U.S. Food and Drug Administration (FDA) for manufacturers of medical devices, and it depends on both the intended use and their contact with body surfaces, spaces and luids. For devices that come into direct or indi-rect contact with cardiovascular and lymphatic systems, the limit is 0.5 UE/mL or 20 UE/device. However, regarding devices that come into contact with the cerebrospinal luid, the limit is 0.06 UE/mL or 2.15 UE/device. Nonetheless, there are not established or regulated limits for endotox-ins in sterilized surgical endotox-instruments, or any requirement to conduct tests that evaluate their presence(7-9).
In this respect, the hypothesis that there might be en-dotoxins in surgical instruments is presented and, therefore, they can contribute to the aseptic loosening of orthopedic implants. herefore, the objective of this study was to in-vestigate the presence of endotoxins in sterilized surgical instruments used in hip arthroplasties.
METHOD
A descriptive exploratory study was conducted to inves-tigate endotoxins in sterilized surgical instruments used in hip arthroplasty surgeries.
he study was conducted in a public teaching hospital that provides high complexity care in traumatology, located in the city of Belo Horizonte, in the state of Minas Gerais. his hospital has a surgical center with six operating rooms and a sterile processing department (SPD), where surgical instruments are processed.
Speciic sets of surgical instruments for hip arthroplasty contain about 50 pieces (Figure 1). hese were analyzed along with the nurse coordinator of the SPD and the or-thopedic physician coordinator of hip surgery, with the aim to classify instruments that present diiculty in the removal of bone and blood residues during the cleaning for further sterilization. Six types of surgical instruments were selected, namely: acetabulum rasp, femoral rasp, femoral head re-mover, chisel box, lexible bone reamer and femoral head test, totaling 29 pieces.
Source: author’s ile.
Figure 1 – Set of surgical instruments for hip arthroplasty – Belo Horizonte, Minas Gerais, Brazil, 2014.
he instruments’ sample size was calculated considering studies with the aim to deine if a speciic event occurs or not in a given population(10). More speciically, to identify the presence of endotoxins in the selected instruments used in hip arthroplasties. In this situation, the calculation of the sample size (n) follows:
log(1− p) n = log( )b
where: 1 – b = power of the study (usually b = 0.05 or b = 0.10)
p = expected proportion of the event’s occurrence in the population
In the sample calculation, an expected proportion (p) of at least 10% of presence of endotoxin in instruments (p = 0.10) and a power of 90% (b = 0.10) were considered. In this case, the sample size must include at least 22 instruments.
Goveia VR, Mendoza IYQ, Guimarães GL, Ercole FF, Couto BRGM, Leite EMM, et al. instruments. It is important to note that the tests were
con-ducted according to the material provided by the hospital, considering that it was not possible to test the 29 selected pieces initially, in none of the three stages.
In the SPD daily routine, the sterilization processes are monitored by physical, chemical and biological indicators. he unit uses drinking water for the processing of materi-als, whose standards are evaluated every four months, ac-cording to the edict MS No. 2914/2011(11) of the Brazilian Ministry of Health. he validation of the steam sterilization process in the SPD is conducted every year for sterilization assurance, which includes the qualiication of equipment regarding their installation, operation and performance. Laboratorial analyses were conducted in the microbiology department of the Instituto de Ciências Biológicas of the Universidade Federal de Minas Gerais (ICB/UFMG, as per its acronym in Portuguese).
he sterilized surgical instruments ready for use were analyzed with the EndosafeTM gel-clot LAL method (Limulus Amebocyte Lysate by Charles River Laboratories, Inc. USA) for the detection of endotoxins, according to standards established by the US Pharmacopoeia(12).
Using the aseptic technique in laminar low cabinet, the instruments were transferred to a sterile container with 200mL of water for apyrogenic injection (AI). hey were submitted to sonication through the Bransonic 2510R-MT Ultrasonic Cleaner for 30 seconds, at a frequency of 42KHz and vortex agitation for 15 seconds. After this process, an aliquot of 20mL of AI obtained from the processing of each instrument was transferred to an apyrogenic conical tube, for conducting the endotoxins detection test.
he biological principle of the EndosafeTM LAL test de-rives from the blood coagulation observed in the American horseshoe crab Limitus polyphemus, when in contact with lipopolysaccharides (LPS) present in Gram-negative bac-teria. he test used presents lambda (λ) sensitivity of 0.125 UE/mL, which corresponds to 0.025 ng/mL.
he Endosafe™ LAL and the standard endotoxin were reconstituted with AI, according to the manufacturer’s guidelines. After the reconstitution of the endotoxin, series of dilutions were conducted to conirm the LAL sensitivity. he test tubes were prepared in duplicate with 100µL of the diluted solutions and for the positive controls, according to the manufacturer’s indication. hen, 100µL of LAL reagent were added. he same procedure was conducted for the ex-periment tubes, being 100µL of the conical tubes trans-ferred to the test tubes in duplicate, and 100µL of LAL reagent were added.
he test tubes were incubated in water-bath for one hour, at the temperature of 37 ± 1°C. he reading of each tube was conducted according to the manufacturer’s in-structions, that is, by direct observation of gel formation, being the result interpreted as positive when the tube is inverted to 180o and the gel maintains its integrity. he negative result is characterized by the absence of gel or a viscous mass that does not adhere to the bottom of the tube when it is inverted. All glassware used in the experiments was previously depyrogenazed through a method previously validated by the manufacturer.
For statistical analysis, the proportion of contamination from endotoxin was estimated by means of point estimation and by 95% conidence interval.
he research project was approved by the Research Ethics Committee of the Universidade Federal de Minas Gerais – UFMG, under protocol no ETIC 0300.0.203.000-10.
RESULTS
he surgical instruments submitted to analysis for the detection of endotoxins totaled 60 pieces and are presented in Table 1.
Table 1 – Distribution of complex surgical instruments obtained for test: risk of contamination from endotoxins – Belo Horizonte, Minas Gerais, Brazil, 2014.
Type of
instrument N
END
≥ 0.125
UE/mL
Risk of contamination by endotoxins
95% conidence
interval for risk of endotoxins
Acetabulum
rasp 19 0 — —
Femoral rasp 15 4 27% [5%; 49%]
Femoral head
remover 1 0 — —
Chisel box 1 0 — —
Initial reamer 2 0 — —
Femoral
head test 12 0 — —
Acetabulum
test 5 0 — —
Flexible bone
reamer 5 4 80% [28%; 99%]
Total 60 8 13% [6%; 26%]
In the irst stage, the hospital provided 25 sterilized surgical instruments for analysis, namely: eight acetabulum rasps, eight femoral rasps, one femoral head remover, one chisel box, one initial reamer and six femoral head tests. In the second stage, 17 instruments were provided, being eight acetabulum rasps, four femoral rasps and ive acetabulum tests. In the third stage, 18 instruments were provided, be-ing three acetabulum rasps, three femoral rasps, one initial reamer, six femoral head tests and ive lexible bone reamers.
After tests were conducted in the irst stage, consistent gel formation was observed, with positive analysis for endo-toxins in four femoral rasps among the 25 surgical instru-ments. Tests in the second stage did not show consistent gel formation in any of the 17 surgical instruments tested. Tests in the third stage showed consistent gel formation with positive analysis for endotoxins in four lexible bone reamers among the 18 surgical instruments.
he positive analysis represents a quantity of ≥0.125 UE/ mL in the solution of the instrument tested. herefore, for 60 instruments submitted to test for the detection of endo-toxins, there was consistent gel formation with positive anal-ysis in eight surgical instruments, corresponding to 13.3%.
DISCUSSION
Endotoxins in surgical instruments of hip arthroplasty
patient safety(13). he conditions for processing surgical in-struments practiced in 249 SPDs were investigated by the health department of England, classifying them by a quality standard. he evaluation had the aim to investigate provision and use of equipment, trained human resources, manage-ment and technical support to the reprocessing and compli-ance with good practice and current legislation. Furthermore, the units were evaluated regarding the adoption of special care for the processing of materials used in procedures with a high risk of transmitting the variant of the Creutzfeldt-Jacob disease. he results showed that 44% of the services were classiied with unacceptable standards, and only 17% were classiied with good standards. In this respect, the govern-ment developed an action plan, announced investgovern-ments to improve the SPDs and a new evaluation was conducted(14).
he presence of endotoxins in 80% of the lexible bone reamers reinforces the technical diiculty in processing this study, reported by professionals who work in SPDs. It is recommended that the solution used for the cleaning of in-struments have contact with all their surfaces; furthermore, composite materials must have their parts dismantled, ac-cording to the manufacturer’s guidelines. In case the clean-ing of all surfaces cannot be performed, residues of organic matter may remain, and if they are not removed before ster-ilization, they may cause harm to patients(15).
In Brazil, SPDs are regulated by the National Health Surveillance Agency (ANVISA, as per its acronym in Portuguese), which established good practice requirements for the processing of health products in 2012. Aspects such as human resources and materials, infrastructure and all processes performed in this area are regulated both for health services and reprocessing companies. Regarding the rinsing water for health products, it must meet drinkability standards; however, the rinsing of critical materials used in surgeries of orthopedic implants must be performed with puriied water(16).
he Brazilian Pharmacopeia establishes standards and deines puriied water as drinking water that was submit-ted to any kind of treatment for the removal of potential contaminants, and the treatment process consists of dis-tillation, ion exchange, and reverse osmosis. It must meet purity requirements and be tested regarding its acidity and alkalinity, oxidizable substances, conductivity, total organic carbon, ammonium, calcium and magnesium, chlorides, nitrates and sulfates; it must be tested for microbiologi-cal safety by the counting of mesophilic microorganisms. Ultra-pure water is the puriied water submitted to addi-tional treatment, which is generally used in laboratory test procedures. he Brazilian Pharmacopeia does not establish a requirement for testing endotoxins in puriied or ultra-pure water(17). herefore, the use of the American guide is necessary to deine endotoxin standards in the water used for processing materials in the SPD(18). It is believed that only making use of the Brazilian regulation to structure the SPD does not ensure good practices associated with the purity or absence of endotoxins in water.
he endotoxins’ role in the aseptic loosening of im-plants is still not clear; however, researchers proved that
endotoxins are at least partially responsible. heir presence increases cellular response to particles generated from the implant, and they probably interact with particle loading, implant movement, mechanical strength and loating head pressure to induce the prosthesis loosening. Studies suggest that endotoxins adhered to an implant interfere in its os-seointegration, causing its loosening(5-19).
In 2005, researchers deined three potential sources of endotoxins to patients with aseptic loosening of implants, namely: (1) before surgery, the implant may contain a sig-niicant amount of endotoxin adhered to its surface; (2) cir-culating endotoxin generated from gut microbiota, minor infections or dental procedures may accumulate in the par-ticles generated from the use of the prosthesis or in the tis-sue around the implant; (3) subclinical bacterial bioilm. he authors airm that microbiological studies have showed the presence of bacteria in the implant surface of patients who presented aseptic loosening, despite the absence of clinical signs of infection(5-19).
Considering the possibility that the water used in the processing of surgical instruments might be infected by Gram-negative bacteria and might be the source of endo-toxins(6), it is important to care about the structural condi-tions in the SPDs, since they are units destined to the pro-cessing of health products. he efective decontamination of surgical instruments is one of the main components of quality care to ensure patient safety(13).
Furthermore, surgical instruments processed by SPDs may become the fourth potential source of endotoxin and contrib-ute to the loosening of orthopedic prostheses. It is important to consider the additional risk associated with the multiple use of orthopedic instruments that usually belong to the pros-thesis supplier, instead of the health service. Consequently, the instruments are used by several health services, which is a factor that may contribute to the development and accumula-tion of bacterial bioilm on their surfaces(20).
Considering the contamination of surgical instruments from endotoxins a complex matter, structural conditions that minimize their presence are necessary. Furthermore, the guide of the Association for the Advancement of Medical Instrumentation (AAMI) establishes four categories of wa-ter used in the reprocessing of medical devices, as well as the characteristics of each one of them, treatment methods and validation of treatment systems(18). Surgical instruments are accessories for the installation of orthopedic prostheses and they should not represent one more risk factor.
Goveia VR, Mendoza IYQ, Guimarães GL, Ercole FF, Couto BRGM, Leite EMM, et al. he results of the present study should be carefully
re-garded, considering that endotoxin tests are recommended both for devices that will be inserted and remain in the pa-tient’s body and for the rinsing water used for reprocessing critical health products. here are scientists who question the lack of regulations and requirements of good practice of biomaterials manufacture, recognizing the need to perform regular endotoxin tests, to report values of all surfaces and to give special attention in the interpretation of results, since the minimum presence of endotoxin may cause a response from the immune system(3,5,19,21).
Although this is an innovative study, which used a methodology not yet validated, it is important to note the fact that the sensitivity to detect endotoxins was established at 0.125 UE/mL.
he fact that drinking water was used to rinse surgi-cal instruments is considered a limitation of this study. However, the regulation regarding the use of puriied water to the rinsing of critical health products was published in March of 2012, with a maximum period of 24 months for the health services to implement the required adjustments.
he materials analyzed by this study were obtained in the SPD, from October to December of 2012, when the imple-mentation project of water treatment by reverse osmosis was object of discussion at the hospital.
CONCLUSION
Presence of endotoxins in 13% of the sterilized ortho-pedic surgical instruments was detected in ≥0.125 UE/ mL. he processing of surgical instruments in the SPD is a complex matter that involves the validation of all stages of the process, especially when there is possibility to pre-vent their contamination, being necessary the adoption of regulations, and national and international guides for qual-ity control.
It is worth mentioning the importance of establishing measures for the control of water used for processing or-thopedic surgical instruments in the SPD. he results of this study suggest the diiculty of cleaning lexible bone reamers, therefore, further studies are required to analyze the impact of this inding and to recommend alternatives for the lexible reamers.
RESUMO
Objetivo: Investigar endotoxinas em instrumentais cirúrgicos esterilizados empregados em artroplastias do quadril. Método: Estudo exploratório, descritivo, desenvolvido em um hospital público de ensino. Foram selecionados seis tipos de instrumentais, a saber: raspa acetabular, raspa femural, saca-cabeça de fêmur, formão box, fresa de fêmur e cabeça de prova de fêmur. A seleção foi feita a partir da análise da diiculdade para a remoção de resíduos de sangue e osso durante a limpeza. A amostra foi constituída por 60 instrumentais cirúrgicos, que foram testados para endotoxinas em três momentos distintos. Foi utilizado o método de gel-clot pelo Limulus Amebócito Lisado (LAL) Endosafe™. Resultado: Houve formação de gel consistente com análise positiva em oito instrumentais, o que corresponde
a 13,3%, sendo quatro raspas de fêmur e quatro fresas de fêmur. Conclusão: Foram detectadas endotoxinas em quantidade ≥0,125 UE/mL em 13,3% dos instrumentais testados.
DESCRITORES
Endotoxinas; Instrumentos Cirúrgicos; Artroplastia de Quadril; Enfermagem Ortopédica; Enfermagem de Centro Cirúrgico.
RESUMEN
Objetivo: Investigar las endotoxinas en instrumentales quirúrgicos esterilizados empleados en artroplastias de la cadera. Método: Estudio exploratorio, descriptivo, desarrollado en un hospital público de enseñanza. Fueron seleccionados seis tipos de instrumentales, a saber: raspa de acetábulo, raspa femoral, sacacorchos (para extraer la cabeza femoral), gubia quirúrgica, fresa femoral y cabeza femoral de prueba. La selección se hizo desde el análisis de la diicultad para la retirada de residuos de sangre y hueso durante la limpieza. La muestra estuvo constituida de 60 instrumentales quirúrgicos, que fueron puestos a prueba para endotoxinas en tres momentos diferentes. Se utilizó el método de geliicación (Gel-clot) Lisado de Amebocitos de Limulus (LAL) Endosafe™. Resultado: Hubo formación de gel
consistente con análisis positivo en ocho instrumentos, lo que corresponde a el 13,3%, siendo cuatro raspas femorales y cuatro fresas femorales. Conclusión: Fueron detectadas endotoxinas en cantidad ≥0,125 UE/mL en el 13,3% de los instrumentos probados.
DESCRIPTORES
Endotoxinas; Instrumentos Quirúrgicos; Artroplastia de Reemplazo de Cadera; Enfermería Ortopédica; Enfermería de Quirófano.
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